Triple to emit x86_64-apple-macosx as elf

Hi,

I'm trying to get an ELF object file for the x86_64-apple-macosx triple but adding -elf to the end like
x86_64-apple-macosx-elf doesn't change it. In the past I used x86_64-pc-win32-elf, which changed the win32 output from COFF to ELF. Is there an equivalent option for mach-o?